JP4403059B2 - Fixing member, fixing member surface layer forming method, fixing device, fixing method, and image forming apparatus - Google Patents

Description

  The present invention relates to a toner fixing roller and a fixing device, and more particularly to a fixing device, a fixing method, and a fixing roller. In particular, the present invention relates to an improvement in heating efficiency of a layer that requires releasability from the outermost toner.

Various methods and apparatuses have been developed for the fixing process of electrophotography, but the most common method at present is a pressure heating method using a heat roller. The pressure heating method using a heating roller allows the toner image surface of a fixing sheet to pass through the surface of a heat roller formed with a material having a releasability with respect to the toner (mainly fluorocarbon resin) under pressure. Is used for fixing. What is important in the fixing process is that no offset of toner particles from the support to the fuser member occurs during normal operation. The offset of the toner particles on the fuser member may then be transferred onto other parts of the apparatus or onto the support in later copy cycles, thus increasing scumming.
The toner particle offset includes so-called hot offset and cold offset.
The hot offset is an offset phenomenon that occurs when the toner layer is divided when the toner is overheated and the cohesive force of the toner is less than the adhesive force between the fixing roller and the paper in the heat roller fixing method. Also called high temperature offset. The set temperature of the roller when this occurs is the hot offset temperature.
Cold offset means that in the heat roller fixing method, when the vicinity of the interface between the toner and the paper is not sufficiently melted, a part of the toner image is removed by the adhesive force or electrostatic attraction force with the fixing roller. Also called low temperature offset. In addition, the set temperature of the roller when this occurs is the cold offset temperature.

In other words, the hot offset occurs when the toner particles are liquefied due to the temperature rise of the toner and the temperature of the molten toner is increased to a temperature at which the fixing operation is performed, and a part of the toner remains on the fixing member. “Hot offset temperature” or “reduction in hot offset temperature” is a measure of the release properties of the fuser roll, and it is therefore desirable to provide a fusing surface that has the low surface energy and provides the necessary peel.
Although many materials function initially with good release properties in continuous use, they are prone to contamination by paper fibers, paper strips and toner as a result of toner hot offset, thus reducing the surface energy of the roll. Increase and decrease peel performance. In addition, once the roll is contaminated, the hot offset temperature begins to drop and can approach levels below or below the minimum temperature required to fix the toner image, so that incomplete fixing of the toner image and It provides both toner offset to the fuser roll of the toner image. Once the fuser roll begins to become contaminated, the contaminants also migrate to the pressure roll. Thus, releasability is an important measure.
Further, since the fixing roller serves to transfer heat to the toner, the fixing roller is set so as to minimize heat transfer from the heating element to the toner.

  Various improvements have been made to the heat conductivity of the fixing roller. In order to form a high thermal conductive composite, fillers are dispersed in a matrix resin, and the fillers are mutually connected through a metal network formed in a network by a low melting point metal or eutectic alloy having a melting point of 500 ° C. or less. (For example, refer patent document 1). However, since this merely forms a high thermal conductive composite, it does not have releasability from the toner, which is the most important characteristic of the fixing roller, and the toner is fixed immediately. I have it. In consideration of releasability, the present applicant has proposed that the surface of the fixing roller is composed of a nickel coating mixed with fluororesin particles to improve thermal conductivity (see Patent Document 2). However, since this also involves mixing fluorine resin particles in the nickel coating, the releasability on the surface of the fixing roller is still insufficient. In addition, when an electromagnetic induction method is desired, an eddy current needs to flow, so that an electric conductor separated by an insulator cannot be expected to generate sufficient heat.

There is an example using a crystallized graphite sheet for the purpose of improving thermal conductivity (see, for example, Patent Document 3). However, this also requires a release layer on the crystallized graphite sheet in order to ensure releasability, and there is a limit to improving the thermal conductivity.
There has been proposed a fixing roller in which a non-adhesive release resin layer is coated on the surface of a metal roller, wherein the resin layer contains a flaky metal (for example, see Patent Document 4). However, when this roller is used, the surface is scraped, flake-like metal comes out on the surface, and the toner is fixed. In order to prevent this, flakes are distributed inside, but when the fluororesin having poor thermal conductivity on the surface becomes thick, the effect of thermal conductivity becomes very small.

Japanese Patent Application Laid-Open No. 06-196884 Japanese Utility Model Publication No. 01-164463 JP 2001-117402 A Japanese Patent Laid-Open No. 04-067187

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing member that can increase fixing heat efficiency and improve image forming productivity by using a release layer having good thermal conductivity.

In the first aspect of the present invention, the fixing member has a heating member, contacts the recording medium carrying the unfixed toner, heats the recording medium, and fixes the unfixed toner. It has the base material which comprises a rotary body, and the surface layer in which the good conductor of heat was mixed in the fluororesin material provided in the outer peripheral side of this base material .
The surface layer includes a fluororesin material exhibiting granularity that is aggregated so as to surround the good heat conductor.
The “good conductors of heat” aggregated so as to surround the fluororesin material having graininess are in contact with each other, and the cross section of the fluororesin material having graininess is exposed on the surface of the surface layer.
According to a second aspect of the present invention, in the fixing member of the first aspect, a metal is used as the good heat conductor.

According to a third aspect of the present invention, in the fixing member according to the second aspect, any of gold, silver, copper, lead, nickel, zinc, iron, aluminum, magnesium, titanium, bismuth, and tin is used as the good heat conductor. It is characterized by the fact that it is a metal grain containing one or more.
According to a fourth aspect of the present invention, in the fixing member of the first aspect, an insulating inorganic compound is used as the good heat conductor.

According to a fifth aspect of the present invention, in the fixing member according to the fourth aspect, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride are used as the good heat conductor. , Boron oxide, boron nitride, boron oxynitride, magnesium oxide, titanium oxide, sialon, and beryllia.
According to a sixth aspect of the present invention, in the fixing member according to any one of the first to fifth aspects, a contact angle of the surface layer with respect to water is 80 ° or more.

According to a seventh aspect of the present invention, in the fixing member according to any one of the first to sixth aspects, the thickness of a portion of the surface layer that is aggregated so as to surround the good heat conductor is that of the base material. It is 30 μm or less in a cross section parallel to the surface.
According to an eighth aspect of the present invention, in the fixing member according to any one of the first to seventh aspects, the fluororesin material is 6 g / 10 min at an MFR (melt flow rate) (372 ° C., load 5 kg). It is characterized by the following.
9. The fixing member according to claim 1, wherein the fluororesin material can have at least one of a PFA having a large molecular weight and a PFA containing carbon.

According to a ninth aspect of the present invention, in the fixing member according to any one of the first to eighth aspects, the surface layer has a surface roughness of 2 μm or less as Rz (10-point average roughness). It is characterized by.
According to a tenth aspect of the present invention, in the method for producing the surface layer of the fixing member according to any one of the first to ninth aspects, a fluororesin is used as the resin material, and the heat treatment is performed on the fluororesin particles. Using part or all of a good conductor surface coated, electrostatically coated on the rotating body, and then heated to form a film, and the surface of the film was polished to expose the cross section of the fluororesin material. It is characterized by.
According to an eleventh aspect of the present invention, in the method for producing the surface layer of the fixing member according to any one of the first to ninth aspects, a fluororesin is used as the resin material, and the thermal resin is applied to the fluororesin particles. Use part or all of a good conductor surface-coated, disperse it in an aqueous solution , apply the coating on the rotating body with the coating liquid, heat it to form a film, and polish the surface of the film The cross section of the fluororesin material is exposed .
According to a twelfth aspect of the present invention, the recording medium is nipped and conveyed between the fixing member according to any one of the first to ninth aspects and a contact portion of a rotating body that rotates in contact with the fixing member. A fixing device for fixing unfixed toner is characterized.

According to a thirteenth aspect of the present invention, in the fixing device according to the twelfth aspect , the rotating body that rotates in contact with the fixing member also has a heating member.
According to a fourteenth aspect of the present invention, in the fixing device according to the twelfth or thirteenth aspect , a release agent is applied to at least one of the two rotating bodies ( the rotating body that rotates in contact with the fixing member and the fixing member). An application means for applying is provided.

According to a fifteenth aspect of the present invention, in the fixing device according to any one of the twelfth to fourteenth aspects, a pressure per unit area of a contact portion where the two rotating bodies come into pressure contact is 0.5 [kgf / cm. ² ] It is characterized in that it is set to be at least.
According to a sixteenth aspect of the present invention, in the fixing device according to any one of the twelfth to fifteenth aspects, the pressure per unit area of the contact portion where the two rotating bodies come into pressure contact is 4.0 [kgf / cm]. ² ] It is characterized by being set to be as follows.
According to a seventeenth aspect of the invention, there is provided a fixing method for fixing a wax-containing toner using the fixing member according to any one of the first to ninth aspects.
According to an eighteenth aspect of the invention, there is provided a fixing method in which the fixing device according to any one of the twelfth to sixteenth aspects is used and a release agent is applied to at least one of the two rotating bodies.
According to a nineteenth aspect of the invention, there is provided an image forming apparatus using the fixing device according to any one of the twelfth to sixteenth aspects.

The present invention can provide a fixing member with good heat transfer characteristics and a highly efficient fixing device with a small addition of a good heat conductor. Other effects are described below.
Toner dust caused by electrostatic repulsion can be prevented by making the fixing roller potential close to ground.
With respect to the negatively charged toner, the fixing roller is negatively charged, and toner adhesion can be reduced.
It is possible to prevent the thermal good conductor from spreading during heating, and to efficiently produce a surface layer structure of the fixing member with good releasability with a small addition of the good thermal conductor.
By improving the releasability with the toner, a durable fixing method can be obtained.
In order to prevent toner adhesion, the toner can be fixed within the limit of the releasability of the wax or the release agent.
An image forming apparatus having characteristics of high durability, high image quality, and energy saving can be obtained.
Further effects are described directly in the examples.

FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.
In the figure, reference numeral 1 is a photosensitive member, 2 is a charging roller, 3 is an optical scanning device, 4 is a developing device, 5 is a transfer roller, 6 is a fixing device, 7 is a cleaning device, 8 is a static eliminating device, and 9 is a recording medium. Each is shown.
The image forming apparatus can obtain an image by executing a known electrophotographic process, and has a photoconductive photoreceptor 1 formed in a cylindrical shape as an image carrier. Around the photosensitive member 1, a charging roller 2, a developing device 4, a transfer roller 5, a cleaning device 7, and a static eliminating device 8 are disposed as charging means. In addition, the image forming apparatus includes an optical scanning device 3 and a fixing device 6. A corona charger can also be used as the charging means. The optical scanning device performs exposure by optical scanning on the surface of the photoreceptor between the charging roller and the developing device.

  When image formation is performed, the photosensitive member 1 is rotated clockwise in FIG. 1, the surface thereof is uniformly charged by the charging roller 2, and then the surface of the photosensitive member 1 is electrostatically exposed by the light scanning device 3. A latent image is formed. This electrostatic latent image is reversely developed by the developing device 4 to form a toner image on the surface of the photoreceptor 1. This toner image is superimposed on the recording medium 9 sent to the transfer portion by a paper feeding mechanism (not shown) at the timing when the toner image on the photosensitive member 1 moves to the transfer position, and is recorded by the action of the transfer roller 5. Electrostatic transfer to the medium 9 is performed. The recording medium 9 to which the toner image has been transferred is discharged to the outside after the toner image is fixed by the fixing device 6. After the toner image is transferred, residual toner and paper dust are removed from the surface of the photoreceptor 1 by the cleaning device 7, and the charge is removed by the charge removal device 8.

FIG. 2 is a schematic view of the fixing portion.
In the figure, reference numeral 21 denotes a temperature detection element, 23 denotes a halogen heater, 24 denotes a fixing roller, 25 denotes a surface layer of the fixing roller, 26 denotes a pressure roller, S denotes a recording sheet, and TI denotes a toner image to be fixed.
The fixing roller 24 in pressure contact with the pressure roller 26 rotates clockwise, and the recording sheet S having the toner image TI to be fixed is sandwiched between the fixing roller 24 and the pressure roller 26 and conveyed in the direction of the arrow. It is like that. A heating halogen heater 23 is heated from inside the fixing roller. The surface temperature of the fixing roller 24 is detected by the temperature detection element 21. The surface layer 25 of the present invention is formed on the surface of the fixing roller 24.

FIG. 3 is a cross-sectional view showing a configuration example of the surface layer in the fixing roller of the present invention.
In the figure, reference numeral 51 denotes a fluororesin portion, and 52 denotes an aggregate portion of a good heat conductor. This figure shows a cross section (surface of the surface layer) in a direction parallel to the surface of the fixing roller substrate. This direction is called a horizontal direction for convenience.
The surface layer includes a fluororesin material portion 51 exhibiting granularity that is aggregated so as to surround the good conductor 52 of heat. The heat good conductors 52 aggregated so as to surround the granular fluororesin material portion 52 are in contact with each other.
The portion of the fluororesin portion 51 exposed in the cross section occupies a large area in the cross section, and ensures releasability. The heat good conductor aggregated portion is about 5% in terms of area, but most of the aggregate is agglomerated, so the contribution of thermal conductivity is large.
Since the agglomerated portions are in continuous contact with each other in all directions, the thermal conductivity in the horizontal direction is also high. Here, the agglomeration refers to a part in which the volume of the good thermal conductor exceeds the volume of the fluororesin in the local volume part.

FIG. 4 is a view showing a cross section perpendicular to the surface of the fixing roller substrate.
In the figure, reference numeral 27 denotes a roller base material.
For convenience, the cross-sectional direction shown in FIG. As can be seen in the figure, the agglomerated portions are in continuous contact with each other in all directions even in the vertical direction, contributing to an improvement in thermal conductivity.

As the fluororesin used in the present invention, a resin having a good melt film-forming property by firing and a relatively low melting point (preferably 250 to 300 ° C.) is preferably selected. Specific examples include fine powders of low molecular weight polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). It is done.
As the low molecular weight polytetrafluoroethylene (PTFE) powder, Lubron L-5, L-2 (Daikin Industries), MP1100, 1200, 1300 and TLP-10F-1 (Mitsui DuPont Fluorochemical) are known. As the tetrafluoroethylene-hexafluoropropylene copolymer (FEP) powder, 532-8000 (DuPont) is known. As the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), MP-10, MP102, (Mitsui DuPont Fluorochemical) are known. In particular, MP103, MP300 (Mitsui Dupont Fluorochemical), AC-5600, AC5539 (Daikin Industries) and the like are suitable for the present invention as those having a low MFR (melt flow rate: heat fluidity) and low fluidity. In general, a material having low fluidity can be obtained by increasing the molecular weight and limiting the mobility of the molecule. Further, it is possible to limit the mobility of molecules by mixing fine particles, for example, in the order of μm or less. For this purpose, for example, fine carbon is used from the viewpoint of dispersibility.
Moreover, as a metal filler, fillers, such as gold | metal | money, silver, copper, lead, nickel, zinc, iron, aluminum, magnesium, titanium, can be used. These spherical, acicular fillers, and fibrous fillers are used to fix metal powder around the fluororesin.
As a good heat conductor, the following insulating inorganic compounds can be used in addition to metals.
That is, as an insulating inorganic compound, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, boron oxide, boron nitride, boron oxynitride, magnesium oxide, oxidation Titanium, sialon, beryllia, etc. can be used. Hereinafter, when meaning at least one of a metal material and a non-metal material, it is simply expressed as “a metal material and a non-metal material” in order to simplify the expression.

FIG. 5 is a diagram for explaining the relationship between the fluidity of the fluororesin and the thermal conductivity. FIG. 4A shows the case of a resin material having a high thermal fluidity (MFR), and FIG. 4B shows the case of a resin material having a low MFR. In the same figure, the case where the fine particle of Ag (silver) is used as a heat good conductor is shown.
When powder coating is performed with MP102 having a large MFR and baking is performed, as shown in FIG. However, when a fluororesin powder having a small MFR is used, it becomes as shown in FIG.
As described above, the good heat conductor aggregates, so that a thermal conductivity that cannot be achieved in a simply dispersed state can be obtained, and a temperature drop during fixing of the fixing member can be reduced. Moreover, since the amount of heat added to the good conductor can be reduced, it is possible to reduce the releasability substantially to a negligible level. In addition, since the metal is electrically conductive, the structure is such that the surface layer is electrically connected to the ground, and the potential of the roller surface can be close to the ground potential.
In addition, the surface layer can be floated electrically because of the insulating property of the good thermal conductor, the potential due to frictional charging can be maintained, and the potential on the roller surface can be kept away from the ground.

In the fixing member of the present invention, the contact angle of the surface layer 15 with respect to water is 80 ° or more. As a result, when using a wax-containing toner, the wax that comes out of the toner and adheres to the surface layer side is not repelled on the surface layer. The recording material does not wrap around the fixing member functioning as an adhesive.
When the contact angle with water is less than 80 °, the toner resin itself is too wet and the adhesion force of the toner resin itself increases rapidly, exceeding the effect of preventing adhesion by wax, and the whole toner moves to the surface layer side, resulting in poor fixing. In the present invention, the contact angle was measured by forming a flat test piece of the surface layer material of the fixing member and measuring it at room temperature with a CA-X type manufactured by Kyowa Interface Science Co., Ltd. at a room temperature.
As a method for adjusting the contact angle of the fixing member with respect to the surface layer 15 within the range of 80 ° or more, the blending ratio of the fluororesin that is the material for forming the surface layer 15 and the heat good conductor is changed to change the contact angle with respect to water. There is a way to control. In this case, the contact angle with respect to water can be controlled by a combination of the kind of fluororesin and the good thermal conductor, the mixing method, and the heating temperature.
Further, when the surface layer is formed so that the aggregated portion of the heat good conductor of the surface layer 15 has a maximum width portion of 30 μm or less in an arbitrary cross section, the metal material and the nonmetal material portion which are inferior in non-adhesiveness to fluororesin Even if it is exposed on the surface, the area where the toner directly contacts the metal material and the non-metal material portion becomes small, so that the structure is advantageous for preventing the offset.

FIG. 6 is a view showing an apparatus for fixing metal powder around a fluororesin.
In the figure, reference numeral 151 is a main body casing, 155 is a rotor blade, 158 is a stator, 159 is a discharge valve, 162 is a rotating rotor, 163 is a recycling pipe, 164 is a raw material charging chute, 168 is an impact chamber, and 177 is a stator jacket. Show.
The figure shows an overview of a hybridization system manufactured by Nara Machinery Co., Ltd.
In this apparatus, the powder particles and other fine solid particles supplied from the raw material charging chute 164 are instantaneously generated by a plurality of rotor blades 155 disposed in a rotating rotor 162 that rotates mainly at high speed in the impact chamber 168. In addition, the fine particles collide with the surrounding stator 158 to disperse the powder particles or other fine solid particles in the system while releasing the aggregation, and at the same time, other fine solid particles on the powder particle surface. Is attached by electrostatic force, van der Waals force or the like, or in the case of powder particles only, the particles are rounded or spheroidized. This state advances as the particles fly and collide. In other words, the particles are processed by passing through a recycle pipe 163 a plurality of times along with the flow of the air flow generated by the rotation of the rotor blade 155. Further, when the particles are repeatedly hit from the rotor blade 155 and the stator 158, other fine solid particles are uniformly dispersed and fixed on the surface of the powder particles or in the vicinity thereof. The prepared powder alone or a mixture of a normal fluororesin and the prepared powder is applied by electrostatic coating or wet coating and baked to prepare a surface layer.

Ex. 1: Ag powder (average particle size 0.5 μm) in PFA powder (MP102: 372 ° C., MFR 14 g / 10 min at a load of 5 kg, average particle size φ20 μm) is mixed in an amount that makes Ag 10% in terms of volume. 6 was put into the apparatus shown in FIG. 6 and Ag powder was fixed on the PFA powder. It was confirmed by observation by SEM that Ag was in a state of substantially covering the PFA powder.
The measurement conditions of MFR are common in all the following examples.
Ex. 2: Similarly, in PFA powder (MP103: MFR 6 g / 10 min, average particle diameter φ20 μm), the same Ag powder (average particle diameter 0.5 μm) as described above is mixed in an amount such that Ag becomes 10%. The Ag powder was put on the PFA powder. It was confirmed by observation by SEM that Ag was in a state of substantially covering the PFA powder.

These two powders were electrostatically coated on an aluminum substrate, baked at 380 ° C., melted the resin, cooled, and peeled from the substrate to prepare a sample. Thereby, a sheet having a thickness of 100 μm was produced, and the thermal diffusivity was measured by a scanning laser heating AC method. And heat conductivity was calculated and calculated | required from the volume specific heat measured separately. Ex. 1 is 0.26 (W / mK), Ex. 2 was 1.31 (W / mK), which was very effective.
An electrostatic coating is applied to an aluminum tube that becomes the core metal of the fixing roller, and the resin coated at 380 ° C. is melted and then cooled, and this is polished with corundum particles to have a surface roughness Rz of 2 μm or less. The fixing roller was manufactured. The final thickness of the surface layer was 40 μm. This roller was mounted on an image forming apparatus MF4570 manufactured by Ricoh Co., Ltd. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. Furthermore, the cold offset temperature is EX. 2 is about 10 ° C lower.

[Comparative Example 1]
Ex. 2 is mixed with PFA powder (MP103: MFR 6 g / 10 min, average particle diameter φ20 μm) of Ag scale-like powder (average particle diameter 30-80 μm) in an amount equivalent to 10% in terms of volume, An electrostatic coating is applied to an aluminum tube that becomes the core metal of the fixing roller, and the resin coated at 380 ° C. is melted and then cooled, and this is polished with corundum particles to have a surface roughness Rz of 2 μm or less. The fixing roller was manufactured. The final thickness of the surface layer is 40 μm. This roller was mounted on the image forming apparatus MF4570. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. About 9000 sheets, toner adhered to the roller. When the portion was observed, 50-60 μm of Ag was exposed, and the toner adhered to the portion. Furthermore, the cold offset temperature was almost the same as that of the genuine product.

Ex. 3: Ag powder (average particle size 0.5 μm) was mixed with PFA powder (MP102: MFR 14 g / 10 min, average particle size φ20 μm) in an amount of 10% Ag in terms of volume, as shown in FIG. The Ag powder was put on the PFA powder. It was confirmed by observation by SEM that Ag was in a state of substantially covering the PFA powder.
Ex. 4: Similarly, Ag powder (average particle size 0.5 μm) was mixed with carbon-containing PFA powder (MFR 6 g / 10 min, average particle size φ20 μm) in an amount equivalent to 10% Ag in terms of volume, It put into the apparatus and Ag powder was made to adhere on PFA powder. It was confirmed by observation by SEM that Ag was in a state of substantially covering the PFA powder.

These two powders were electrostatically coated on an aluminum substrate, baked at 380 ° C., melted the resin, cooled, and peeled from the substrate to prepare a sample. Thereby, a sheet having a thickness of 100 μm was produced, and the thermal diffusivity was measured by a scanning laser heating AC method. And heat conductivity was calculated and calculated | required from the volume specific heat measured separately. Ex. 3 is 0.26 (W / mK), Ex. 4 was 1.52 (W / mK), which was very effective.
An electrostatic coating is applied to an aluminum tube that becomes the core metal of the fixing roller, and the resin coated at 380 ° C. is melted and then cooled, and this is polished with corundum particles to have a surface roughness Rz of 2 μm or less. The fixing roller was manufactured. The final thickness of the surface layer was 40 μm. This roller was mounted with the image forming apparatus MF4570. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. Further, the cold offset temperature was adjusted to Ex. 4 is lowered by about 10 ° C.

Ex. 5: Ni powder (average particle size 1.2 μm) is mixed with PFA powder (MP102: MFR 14 g / 10 min, average particle size φ20 μm) in an amount corresponding to 10% Ni in terms of volume, as shown in FIG. The Ni powder was put on the PFA powder. It was confirmed by observation by SEM that Ni was in a state of substantially covering the PFA powder.
Ex. 6: Similarly, Ni powder (average particle size 1.2 μm) is mixed with PFA powder (MP103: MFR 6 g / 10 min, average particle size φ20 μm) in an amount equivalent to 10% Ni in terms of volume, The apparatus was put in and Ni powder was fixed on the PFA powder. It was confirmed by observation by SEM that Ni was in a state of substantially covering the PFA powder.

These two powders were electrostatically coated on an aluminum substrate, baked at 380 ° C., melted the resin, cooled, and peeled from the substrate to prepare a sample. Thereby, a sheet having a thickness of 100 μm was produced, and the thermal diffusivity was measured by a scanning laser heating AC method. And heat conductivity was calculated and calculated | required from the volume specific heat measured separately. Ex. 5 is 0.21 (W / mK), Ex. 6 was 1.27 (W / mK), which was very effective.
An electrostatic coating is applied to an aluminum tube that becomes the core metal of the fixing roller, and the resin coated at 380 ° C. is melted and then cooled, and this is polished with corundum particles to have a surface roughness Rz of 2 μm or less. The fixing roller was manufactured. The final thickness of the surface layer was 40 μm. This roller was mounted on the image forming apparatus MF4570. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. In addition, the cold offset temperature is Ex. 6 is about 10 ° C lower.

Ex. 7: Ni powder (average particle size 1.2 μm) is mixed with PFA powder (MP102: MFR 14 g / 10 min, average particle size φ20 μm) in an amount equivalent to 10% Ni in terms of volume. The Ni powder was put on the PFA powder. It was confirmed by observation by SEM that Ni was in a state of substantially covering the PFA powder.
Ex. 8: Similarly, in a carbon-containing PFA powder (MFR 6 g / 10 min, average particle diameter φ20 μm), Ni powder (average particle diameter 1.2 μm) is mixed in an amount such that Ni is 10% in terms of volume, The apparatus was put in and Ni powder was fixed on the PFA powder. It was confirmed by observation by SEM that Ni was in a state of substantially covering the PFA powder.

These two powders were electrostatically coated on an aluminum substrate, baked at 380 ° C., melted the resin, cooled, and peeled from the substrate to prepare a sample. Thereby, a sheet having a thickness of 100 μm was produced, and the thermal diffusivity was measured by a scanning laser heating AC method. And heat conductivity was calculated and calculated | required from the volume specific heat measured separately. Ex. 7 is 0.21 (W / mK), Ex. 8 was 1.37 (W / mK), which was very effective.
Electrostatic coating is applied to the aluminum tube that is the core metal of the fixing roller, the resin coated at 380 ° C. is melted and then cooled, and this is polished with corundum particles, and the surface roughness Rz is 2 μm or less. The fixing roller was manufactured. The final thickness of the surface layer is 40 μm. This roller was mounted on the image forming apparatus MF4570. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. In addition, the cold offset temperature is Ex. 8 is about 10 ° C lower.

Ag powder (average particle size 0.5 μm) is put into PFA powder (MP103 average particle diameter φ12 μm) by volume conversion into the apparatus shown in FIG. 6 at a volume ratio of 10%, and Ag powder is fixed on the PFA powder. It was. Furthermore, the powder obtained by fixing the Ag powder prepared above to the dry PFA weight in DuPont wet fluorine paint EN700CL with a volume ratio calculated from the specific gravity as 50:50 was mixed at 50:50, stirred and dispersed, and then fixed. An aluminum tube serving as a core metal of the roller was spray-coated, the resin coated at 380 ° C. was melted, cooled, and then polished to obtain a fixing roller. The final thickness was 40 μm.
This roller was mounted on the image forming apparatus MF4570. Through 10,000 sheets of a solid black image, the adhesion state of the toner on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. The thermal conductivity of the separately prepared sample is 1.21 (W / mK), and the cold offset temperature is lowered by about 8 ° C.

In the same manner as in Example 5, a roller was produced, and a surface roughness Rz of 2 μm was produced. A fixing tester using this roller as a fixing unit of the image forming apparatus MF4570 was manufactured, and an unfixed image obtained by the MF4570 was passed through with a different pressure. The test results are shown in Table 1. As shown in the table, when the applied pressure per unit area is 0.5 (kgf / cm ² ) or less, the fixability is very poor, and when the applied pressure is 4.0 (kgf / cm ² ) or more, the fixing roller is moved. Toner adhesion was observed. The fixability was determined simply by rubbing a cotton cloth against the solid image after fixing, with the toner marked on the cloth being regarded as poor fixing.

A roller was prepared in the same manner as in Example 5, and this was polished with corundum particles, and those having a surface roughness Rz of 2 μm or less, 3 μm, 5 μm, and 7 μm were prepared and used as a fixing roller. The thickness of the surface layer is 40 μm. The roller is mounted on the fixing unit of the image forming apparatus MF4570, and an unfixed toner image created after the image forming unit having the same configuration as that shown in FIG. 1 is applied to a test machine (fixing device) having a configuration as shown in FIG. It settled through. Table 2 shows the observation results when fixing was repeated through 10,000 black solid images and the adhesion state of the toner on the roller surface and the winding of the paper were observed.
As a result, it was observed that the effect was effective if the surface roughness was 5 μm or less in Rz. In addition, since the jam of 7 μm frequently occurred with MF4570, the experiment was cancelled.

As described above, according to the present invention, various effects can be obtained. The effects are summarized below.
Even when the strength and hardness of the surface layer of the fixing member are required, by selecting the type of metal, a surface layer that meets the required characteristics can be formed without reducing the heat transfer efficiency.
By controlling the size and distribution of the good heat conductor, the surface energy in a macro form can be maintained in the state of the fluororesin alone, thereby ensuring the releasability of the toner. In other words, the exposure of a small heat good conductor portion has little influence on the macro contact angle, so that the releasability can be ensured.
By adjusting the powder (charging enabled, improved dispersibility), this configuration can be created without significantly changing the conventional fluororesin coating process.
Since the fluidity of the fluororesin is reduced, when the powdery resin is melted by heat to form a film, the diffusion of the good heat conductive powder is small, and the decrease in the thermal conductivity of the agglomerated portion can be suppressed. As a result, a heat path can be easily formed at the agglomerated portion, and the heat conductivity can be increased with a small amount of good conductor powder added.

By increasing the molecular weight or dispersing minute carbon in the fluororesin, a fluororesin powder having low fluidity can be easily produced, and a decrease in the thermal conductivity of the aggregated portion can be suppressed. As a result, a heat path can be easily formed at the agglomerated portion, and the heat conductivity can be increased with a small amount of good conductor powder added.
Since the surface of the fixing member is transferred to the image quality, particularly the solid image, the glossiness is improved by a roller having a smooth surface.
The releasability is improved by the wax in the toner.
The release agent improves the releasability of the toner and the fixing member in contact with the toner.
Fixing with many toners depends on the pressure per unit area in the contact area between the fixing roller and the pressure roller, and in particular, when 0.5 [kgf / cm ² ] or more is applied, image fixability is improved. improves.
Under the condition of 4.0 [kgf / cm ² ] or more, the toner or the release agent such as silicon oil comes out of the toner resin and the roller release layer. If it is below this pressure, mold release property can be maintained.
By using a roller having a surface layer with high releasability and high thermal conductivity, a reliable and energy efficient image forming apparatus can be provided.

1 is a diagram illustrating an embodiment of an image forming apparatus according to the present invention. It is the schematic of a fixing part. FIG. 4 is a cross-sectional view illustrating a configuration example of a surface layer in the fixing roller of the present invention. FIG. 4 is a view showing a cross section perpendicular to the surface of the fixing roller base material. It is a figure for demonstrating the relationship between the fluidity | liquidity of a fluororesin, and heat conductivity. It is a figure which shows the apparatus which adheres metal powder to the circumference | surroundings of a fluororesin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 6 Fixing device 23 Halogen heater 24 Fixing roller 25 Surface layer 26 Pressure roller 27 Fixing roller base material 51 Fluorine resin part 52 Heat good conductor aggregation part

Claims (19)

A fixing member that has a heating member, contacts the recording medium carrying unfixed toner and heats the recording medium to fix the unfixed toner, and the fixing member includes a base material constituting a rotating body; A surface layer in which a good conductor of heat is mixed in the fluororesin material provided on the outer peripheral side of the base material;
The surface layer includes the fluororesin material exhibiting granularity that is aggregated so as to surround the good heat conductor.
The heat good conductors aggregated so as to surround the fluororesin material having the granularity are in contact with each other,
A fixing member, wherein a surface of the surface layer is exposed with a cross section of the granular fluororesin material . The fixing member according to claim 1.
A fixing member using a metal as a good heat conductor . The fixing member according to claim 2,
A fixing member characterized in that a good thermal conductor is made of metal particles containing at least one of gold, silver, copper, lead, nickel, zinc, iron, aluminum, magnesium, titanium, bismuth, and tin. The fixing member according to claim 1.
A fixing member using an insulating inorganic compound as a good heat conductor . The fixing member according to claim 4,
As a good thermal conductor , silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, boron oxide, boron nitride, boron oxynitride, magnesium oxide, titanium oxide, A fixing member comprising grains containing one or more of sialon and beryllia. The fixing member according to any one of claims 1 to 5,
The fixing member, wherein the surface layer has a contact angle with water of 80 ° or more. The fixing member according to any one of claims 1 to 6,
The fixing member, wherein a thickness of a portion of the surface layer aggregated so as to surround a good heat conductor is 30 μm or less in a cross section parallel to the surface of the substrate . The fixing member according to any one of claims 1 to 7,
A fixing member, wherein the fluororesin material has an MFR (melt flow rate) (372 ° C., load 5 kg) of 6 g / 10 min or less. The fixing member according to any one of claims 1 to 8,
  The surface layer has a surface roughness of 2 μm or less as Rz (10-point average roughness). In the method for producing the surface layer of the fixing member according to any one of claims 1 to 9,
  Using part or all of a fluororesin particle surface coated with a good thermal conductor, electrostatically coating the rotating body, heating, forming a film, and polishing the surface of the film, the fluororesin material A method for producing a surface layer of a fixing member, wherein the cross section of the fixing member is exposed.   In the method for producing the surface layer of the fixing member according to any one of claims 1 to 9,
  Part or all of a fluororesin particle coated with a good thermal conductor is used, dispersed in an aqueous solution, coated with the coating liquid on the rotating body, heated, and formed into a film. A method for producing a surface layer of a fixing member, wherein the surface of the film is polished to expose a cross section of the fluororesin material. 10. The fixing member according to claim 1, and the recording medium is nipped and conveyed to a contact portion of a rotating member that rotates in contact with the fixing member to fix the unfixed toner. A fixing device. The fixing device according to claim 12,
  A fixing device characterized in that a rotating body that rotates in contact with a fixing member also has a heating member. The fixing device according to claim 12 or 13,
  A fixing device comprising: an application unit that applies a release agent to at least one of a fixing member and a rotating body. The fixing device according to any one of claims 12 to 14,
  A fixing device, wherein the pressure per unit area of a contact portion where the fixing member and the rotating body come into pressure contact with each other is set to be 0.5 [kgf / cm 2] or more. The fixing device according to any one of claims 12 to 15,
  A fixing device, wherein the pressure per unit area of a contact portion where the fixing member and the rotating body come into pressure contact with each other is set to 4.0 [kgf / cm 2] or less. An electrophotographic image fixing method, comprising: fixing a wax-containing toner using the fixing member according to claim 1. A fixing method using the fixing device according to claim 12, wherein a release agent is applied to at least one of the fixing member and the rotating body. An image forming apparatus using the fixing device according to claim 12.

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